Make CSSValuePair store const CSSValues

third_party/WebKit/Source/core/css/CSSGradientValue.cpp

 /*
  * Copyright (C) 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2015 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 463 matching lines @@
         } else {
             // Normalization failed because the stop set is coincident.
         }
     } else {
         // No normalization required, just add the current stops.
         for (const auto& stop : stops)
             gradient->addColorStop(stop.offset, stop.color);
     }
 }
 
-static float positionFromValue(CSSValue* value, const CSSToLengthConversionData& conversionData, const IntSize& size, bool isHorizontal)
+static float positionFromValue(const CSSValue* value, const CSSToLengthConversionData& conversionData, const IntSize& size, bool isHorizontal)
 {
     int origin = 0;
     int sign = 1;
     int edgeDistance = isHorizontal ? size.width() : size.height();
 
     // In this case the center of the gradient is given relative to an edge in the form of:
     // [ top | bottom | right | left ] [ <percentage> | <length> ].
+    const CSSValue* localValue = value;

[nainar, 2016/07/18 01:47:00]

As per IRL conversation we can just modify value as we were doing before. There
shouldn't be any need to add a new local variable. 

But good to go other than that!

     if (value->isValuePair()) {
-        CSSValuePair& pair = toCSSValuePair(*value);
+        const CSSValuePair& pair = toCSSValuePair(*value);
         CSSValueID originID = toCSSPrimitiveValue(pair.first()).getValueID();
-        value = &pair.second();
+        localValue = &pair.second();
 
         if (originID == CSSValueRight || originID == CSSValueBottom) {
             // For right/bottom, the offset is relative to the far edge.
             origin = edgeDistance;
             sign = -1;
         }
     }
 
-    CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value);
+    const CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(localValue);
 
     if (primitiveValue->isNumber())
         return origin + sign * primitiveValue->getFloatValue() * conversionData.zoom();
 
     if (primitiveValue->isPercentage())
         return origin + sign * primitiveValue->getFloatValue() / 100.f * edgeDistance;
 
     if (primitiveValue->isCalculatedPercentageWithLength())
         return origin + sign * primitiveValue->cssCalcValue()->toCalcValue(conversionData)->evaluate(edgeDistance);
 
@@ skipping 707 matching lines @@
     visitor->trace(m_firstRadius);
     visitor->trace(m_secondRadius);
     visitor->trace(m_shape);
     visitor->trace(m_sizingBehavior);
     visitor->trace(m_endHorizontalSize);
     visitor->trace(m_endVerticalSize);
     CSSGradientValue::traceAfterDispatch(visitor);
 }
 
 } // namespace blink